The present invention relates to a plate element for holding an original in a reproduction device. More particularly, it relates to such a plate element which is provided with light and reflecting upper face at its surface facing toward the original.
A plate element for holding originals, of the above-mentioned general type is known in the art. For example, such a plate element is disclosed in the German Patent No. 2,027,990 and serves for holding an original on a transparent original supporting plate of a copying device during the copying process. The lower side of the holding plate must have an upper face which is as pure white and highly reflective as possible, in which case it comes in its outer appearance as close as possible to the paper upper face of the originals which are to be copied. Such a construction guarantees, on the one hand, that the reproduction of the original has no dark edges when the borders of the transparent supporting plate not exactly coincide with the outer edge of the original, as generally takes place. On the other hand the pure white highly reflective holding plate makes possible to produce clean copies from thin or translucent originals with pure white substratum.
In addition to the required reflection properties, the lower side of the original holding plate element must be paint repellent and dirt repellent. This is necessary in order to prevent dirtying of the plate element during the contact with remains of paint on the original, such as ball pin paste, copying paint, felt pin paste, spirit duplicator ink, etc.
The body of the holding plate, from aesthetical and also from practical considerations, must not be pure white, but instead, it must have relatively dark paint, and the material requirements to the body proper are different as compared with the requirements made to the lower side of the holding plate. For this reason, the original holding plate is often composed of several layers, wherein the body of the holding plate is constituted of polyvinylchloride or rubber, and a white synthetic plastic foil is glued to the lower side of the body. However, the synthetic plastic foil utilized for obtaining the above-mentioned properties must have a relatively high contents of filler which is not sufficiently dirt repellent as a rule and is relatively difficult to connect with the polyvinylchloride layer or rubber layer of the holding plate body proper. In the case when, despite the higher contents of the filler, the foil has sufficient paint repellent properties, it is in practice very difficult to adhere and moreover has a relatively high rigidity which makes difficult manipulation of the original holding plate.